1.
Truedsson, L, et al.
(författare)
Protein HC-IgA complexes carry antibody activities
1988
Ingår i: Scandinavian Journal of Immunology. - : Wiley. - 0300-9475 .- 1365-3083. ; 27:2, s. 201-208
Tidskriftsartikel (refereegranskat) abstract
Polyclonal protein HC-IgA complexes (HC-IgA) were isolated from two different serum pools. Their hydrodynamic volumes were found to be slightly greater than that of monomeric IgA but less than that of dimeric IgA. Sodium dodecyl sulphate (SDS)-polyacrylamide gel electrophoresis of reduced and carboxymethylated complexes followed by immunoblotting showed that the complexes contained normal light and heavy Ig chains, and one polypeptide chain with Mr = 90,000, which carried both IgA alpha chain and protein HC epitopes. Enzyme-linked immunosorbent assays (ELISA) demonstrated that the isolated HC-IgA carried about 0.1 and 4%, respectively, of the antibody activities against one carbohydrate antigen (Yersinia enterocolitica serotype 0:3 lipopolysaccharide) and one protein antigen (rabbit IgG, i.e. antigen for rheumatoid factors) of the IgA populations of the two serum pools. HC-IgA with rheumatoid factor activity could also be demonstrated in the unfractionated serum pool. The binding of HC-IgA in the ELISA was not mediated through its protein HC part. The present observations show that HC-IgA carries antibody activities and constitutes a unique class of IgA complexes, since it does not dissociate under denaturating conditions after reduction. It may represent a further biological potential of the humoral immune system.
2.
Peetre, Christina, et al.
(författare)
A tumor necrosis factor binding protein is present in human biological fluids
1988
Ingår i: European Journal of Haematology. - : Wiley. - 0902-4441 .- 1600-0609. ; 41:5, s. 414-419
Tidskriftsartikel (refereegranskat) abstract
Tumor necrosis factor (TNF) possesses both beneficial and toxic bioactivities. Mechanisms may operate to counteract harmful effects. We have identified a TNF binding protein (TNF-BP), which shows increased levels in serum and urine of patients on regular hemodialysis treatment (RDT). TNF-BP inhibited the specific binding of human recombinant TNF (rTNF) to its cell surface receptor. Results from gel chromatography demonstrated the presence in serum and urine of a macromolecule with an apparent molecular weight of 50,000, which formed a complex with rTNF. A 62-fold purification of TNF-BP from urine of patients on RDT was achieved by ion exchange chromatography and gel chromatography. Partially purified TNF-BP reduced the growth inhibitory effect of rTNF on a susceptible leukemia cell line. TNF-BP may act as a regulator of the biological activity of TNF and could have beneficial effects in certain inflammatory conditions.
3.
Nilsson Ekdahl, Kristina, et al.
(författare)
Effects of epinephrine, glucagon and insulin on the activity and degree of phosphorylation of fructose-1,6-bisphosphatase in cultured hepatocytes.
1987
Ingår i: Biochimica et Biophysica Acta. Molecular Cell Research. - 0167-4889 .- 1879-2596. ; 929:3, s. 318-326
Tidskriftsartikel (refereegranskat) abstract
The effects of epinephrine, glucagon and insulin on the activity and degree of phosphorylation of fructose-1,6-bisphosphatase in isolated hepatocytes maintained in cell culture for 24 h were investigated. Epinephrine caused a rapid decrease in the apparent Km monitored as the activity ratio between the activity at 12.5 and 83 microM fructose-1,6-bisphosphate, reaching a maximum after 5 min. Glucagon caused a slower and less pronounced activation, and insulin caused an equally slow increase in Km. The effect of epinephrine and glucagon was completely reciprocated by insulin and the action of insulin was totally erased by the other two. Glucagon stimulated the incorporation of [32P]phosphate into fructose-1,6-bisphosphatase from about 2.5 to 4.2 mol/mol enzyme and epinephrine to 3.5 mol/mol. The effect of the two hormones acting together was cumulative. Insulin brought about a decrease in the degree of phosphorylation to 2.0 mol/mol. The effect of epinephrine was shown to be caused by the beta-receptors, since it was completely blocked by propanolol (a beta-antagonist) and remained unaffected by the presence of phentolamine (an alpha-antagonist).
4.
Nilsson Ekdahl, Kristina, et al.
(författare)
Fructose-1,6-bisphosphatase from rat liver. A comparison of the kinetics of the unphosphorylated enzyme and the enzyme phosphorylated by cyclic AMP-dependent protein kinase.
1985
Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 260, s. 14173-14179
Tidskriftsartikel (refereegranskat) abstract
A purification procedure for rat hepatic fructose-1,6-bisphosphatase, described earlier, has been improved, resulting in an enzyme preparation with a neutral pH optimum and with both phosphorylatable serine residues present. The subunit Mr was 40,000. Phosphorylation in vitro with cyclic AMP-dependent protein kinase resulted in the incorporation of 1.4 mol of phosphate/mol of subunit and led to an almost 2-fold decrease in apparent Km for fructose-1,6-bisphosphate. In contrast to yeast fructose-1,6-bisphosphatase, fructose-2,6-bisphosphate had no effect on the rate of phosphorylation or dephosphorylation of the intact enzyme. The effects of the composition of the assay medium, with regard to buffering substance and Mg2+ concentration, on the apparent Km values of phosphorylated and unphosphorylated enzyme were investigated. The kinetics of phosphorylated and unphosphorylated fructose-1,6-bisphosphatase were studied with special reference to the inhibitory effects of adenine nucleotides and fructose-2,6-bisphosphate. Unphosphorylated fructose-1,6-bisphosphatase was more susceptible to inhibition by both AMP and fructose 2,6-bisphosphate than phosphorylated enzyme, at high and low substrate concentrations. Both ATP and ADP had a similar effect on the two enzyme forms, ADP being the more potent inhibitor. Finally, the combined effect of several inhibitors at physiological concentrations was studied. Under conditions resembling the gluconeogenic state, phosphorylated fructose-1,6-bisphosphatase was found to have twice the activity of the unphosphorylated enzyme.
5.
Kjellén, Elisabeth, et al.
(författare)
Effect of hyperthermia and/or nicotinamide on the radiation response of a C3H mammary carcinoma
1989
Ingår i: European journal of cancer & clinical oncology. - : Elsevier BV. - 0277-5379. ; 25:12, s. 1733-1737
Tidskriftsartikel (refereegranskat) abstract
The effect of hyperthermia and/or nicotinamide (200 mg/kg of body weight) on the tumour growth delay induced by radiation was evaluated in a C3H mouse mammary adenocarcinoma. The study showed a radiosensitizing effect of hyperthermia and of nicotinamide but the combination of all three modalitites showed no increased tumor growth delay compared to hyperthermia and radiation alone. The tumour growth delay induced by hyperthermia was not modified by nicotinamide.
6.
Malmström, P., et al.
(författare)
Countercurrent Distribution of Lymphocytes from Human Peripheral Blood in an Aqueous Two-Phase System : I. Separation into Subsets of Lymphocytes Bearing Distinctive Markers’
1980
Ingår i: Cellular Immunology. - : Elsevier BV. - 0008-8749. ; 53, s. 39-50
Tidskriftsartikel (refereegranskat) abstract
Lymphocytes from human peripheral blood have been separated by countercurrent distribution in a charged aqueous two-phase system composed of Dextran T 500 and polyethylene glycol 6000 with a cell yield of 59–88% and viability above 90%. A highly reproducible partition pattern was seen with four distinct peaks. Lymphocytes with surface membrane immunoglobulin (SmIg) were located in the first part of the distribution corresponding mainly to peak I. T lymphocytes as detected by E rosetting and α-naphthyl acetate esterase (ANAE) staining showed a broad distribution with a maximum in peaks II and III. ANAE-negative lymphocytes were seen in both extremes of the distribution, corresponding to B cells in the first part and to a population of E− and SmIg− lymphocytes in the last part. Monocytes were present in all fractions with some enrichment in peaks II–IV. Lymphocytes with low-affinity Fc receptors were found in B-cell-containing fractions in the first part of the distribution, but also in the last part. Lymphocytes with high-affinity Fc receptors were detected mainly in peak IV. It is thus demonstrated that peripheral blood lymphocytes can be fractionated into subpopulations enriched in cells with characteristic markers.markers.
7.
8.
Nilsson, B, et al.
(författare)
Components of the alternative pathway
1988. - 1
Ingår i: The Complement System. - : Springer. - 0387182055 ; , s. 23-49
Bokkapitel (övrigt vetenskapligt/konstnärligt)
9.
Nilsson, Bo, et al.
(författare)
Distinctive expression of neoantigenic C3(D) epitopes on bound C3 following activation and binding to different target surfaces in normal and pathological human sera
1989
Ingår i: Molecular Immunology. - : Elsevier BV. - 0161-5890 .- 1872-9142. ; 26:4, s. 383-390
Tidskriftsartikel (refereegranskat) abstract
Binding of C3 to sheep erythrocytes in a serum-free milieu (EAC14oxy2, EAC142) has previously been shown to mimic the antigenic change that occurs upon denaturation of C3 in sodium dodecyl sulphate (SDS), whereby neoantigenic C3(D) epitopes are exposed. The present paper deals with C3 bound to various target surfaces which are known to modulate the functional properties of C3 in different ways. Bound C3 fragments on serum-treated human aggregated gammaglobulin, zymosan, rabbit and sheep erythrocytes, and on circulating immune complexes isolated from sera of patients with rheumatoid arthritis and systemic lupus erythematosus, were shown to be mainly in the iC3b form. By RIAs, employing polyclonal antibodies, the range of C3(D) antigenic epitopes of 125I-labelled SDS denatured C3 expressed by the particle-bound iC3b was monitored. The physiologically bound iC3b on all tested particles expressed wide ranges of C3(D) epitopes and each type of particle-bound C3 exposed its individual range. By competition ELISA specific C3(D)α epitopes were monitored, employing monoclonal antibodies. A distinct difference in the expression of these epitopes was observed in iC3b bound to various test particles in the presence of normal serum and in iC3b present on circulating immune complexes from pathological sera. Considering that the neoantigenic C3(D) epitopes have been shown to be associated with different functions of C3, the distinctive antigenic expression of each type of serum-treated particle might reflect different functional forms of the protein.
10.
Nilsson Ekdahl, Kristina, et al.
(författare)
Development of an immunoassay for the detection of minute amounts of IgG-coated erythrocytes in whole blood: Its application for the assessment of Fc-mediated clearance of anti-D-coated erythrocytes in vivo
1989
Ingår i: Vox Sanguinis. - : Wiley. - 0042-9007 .- 1423-0410. ; 57:3, s. 188-192
Tidskriftsartikel (refereegranskat) abstract
A rapid and sensitive immunoassay for the detection of minute quantities of IgG-coated erythrocytes in whole blood was developed. Washed red blood cells were incubated in two steps with anti-human IgG antiserum followed by 125I-labelled protein A. The assay was able to detect amounts of sensitized erythrocytes as small as 0.5 ml of packed erythrocytes in a total blood volume of 5 liters and hematocrit 40%. A linear relation between increasing amounts of IgG-coated red cells in whole blood and the binding of 125I-labelled protein A was obtained. We applied the technique on the assessment of the removal of IgG anti-D-coated erythrocytes from the circulation of test individuals. T1/2 for the elimination of approximately 4 ml packed red cells sensitized with 62 μg of anti-D in 14 normal subjects was 20±5 min (mean±SEM). A splenectomized person did not clear the injected cells from the circulation during the test period of 70 min. If a standard curve was constructed the total blood volume in the test subjects could be calculated. This value correlated well (r = 0.99) with the blood volume calculated from the height and weight of the test individuals.
